1. Technical Field of the Invention
The present invention relates to thermally insulated containers for storing beverages, and more particularly, for storing hot beverages such as coffee, tea and cocoa. More particularly, the present invention relates to thermally insulated containers for storing beverages, wherein the container is provided with a double wall construction, and wherein internal spacer elements are provided to maintain a minimum distance between the individual walls of the double wall construction.
2. Brief Description of the Related Art
Common single-use coffee cups are primarily made of paperboard or polystyrene. It is well known that the thermal insulation characteristics of polystyrene cups are far superior to those of either kraft paper or bleached paperboard cups. When a hot beverage, such as coffee, tea or cocoa, is poured into a single-use cup, the cup surface temperature rises to a maximum in a few seconds, then slowly cools with the beverage back to ambient temperature. If the maximum cup surface temperature exceeds about 140 degrees F., it is painful for an individual to hold the cup. The surface of a common polystyrene cup, nominally 0.090 in. thick, does not reach this threshold, but that of any single paperboard cup almost always exceeds it.
It is well known to employ various sleeve designs for cups which emphasize insulation capabilities. Exemplary of such sleeves are U.S. Pat. No. 5,205,473 ('473) to D. W. Coffin, Sr., entitled “Recyclable Corrugated Beverage Container and Holder,” U.S. Pat. No. 5,425,497 ('497) to J. Sorensen, entitled “Cup Holder,” U.S. Pat. No. 5,667,135 ('135) to R. J. Schaefer, entitled “Thermal Insulating Sleeve for Drink Cups,” U.S. Pat. No. 5,746,372 ('372) to 0. Spence, entitled “Biodegradable Cup Holder,” U.S. Pat. No. 5,794,843 ('843) to R. S. Sanchez, entitled “Cup Wrap,” U.S. Pat. No. 5,826,786 ('786) to J. Dickert, entitled “Cup Holder Sleeve in Pre-Assembled Flat-Folded Form,” and U.S. Pat. No. 5,842,633 ('633) to R. I. Nurse, entitled “Sleeve for Beverage Cups.” While these references disclose various sleeves for use on beverage containers, none of these are particularly quantitative on the sleeve characteristics needed for good insulation.
It is also known to employ cup designs that emphasize insulation. Exemplary of such cup designs are U.S. Pat. No. 4,007,670 ('670) to J. V. Albano et al., entitled “Insulated Container,” U.S. Pat. No. 4,261,501 ('501) to J. B. Watkins et al., entitled “Laminated Insulated Hot Drink Cup,” U.S. Pat. No. 4,435,344 ('344) to A. Iioka, entitled “Method for Producing a Heat-Insulating Paper Container From a Paper Coated or Laminated With a Thermoplastic Synthetic Resin Film,” U.S. Pat. No. 5,145,107 ('107) to V. K. Silver et al., entitled “Insulated Paper Cup,” U.S. Pat. No. 5,226,585 ('585) to R. Varano, entitled “Disposable Biodegradable Insulated Container and Method for Making,” U.S. Pat. No. 5,460,323 ('323) to J. H. Titus, entitled “Disposable Insulated Container,” U.S. Pat. No. 5,542,599 ('599) to R. E. Sobol, entitled “Biodegradable Thermally Insulated Beverage Cup,” U.S. Pat. No. 5,628,453 ('453) to D. M. MacLaughlin, entitled “Cup With Thermally Insulated Side Wall,” U.S. Pat. No. 5,697,550 ('550) to R. Varano et al., entitled “Multi-Layered Insulated Cup Formed From Folded Sheet,” U.S. Pat. No. 5,713,512 ('512) to R. K. Barrett, entitled “Polymeric Insulated Container,” U.S. Pat. No. 5,752,653 ('653) to M. Razzaghi, entitled “Paper Cup With Air Insulation,” U.S. Pat. No. 5,775,577 ('577) to J. H. Titus, entitled “Disposable Insulated Container With Microflute Structure,” and U.S. Pat. No. 5,839,653 ('653) to R. B. Zadravetz, entitled “Container With Corrugated Wall.” While a number of these references identify the effectiveness of an air gap and the providing of good insulation properties, they do not incorporate the simplicity of a sleeve cut from a single blank, add an air gap which is constructed of hot-melt glue dots, and employ a smooth outside-sleeve surface for printing.
It is apparent from the above that there exists a need in the art for a sleeve construction which is lightweight through simplicity of parts and uniqueness of structure, but which incorporates a sleeve cut from a single blank, adds an air-gap layer, and preserves a smooth outside-sleeve surface for printing. It is the purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure.
U.S. Pat. No. 6,152,363 ('363) to J. A. Rule, entitled “Sleeve Construction for Improved Paperboard Cup Insulation,” teaches a beverage container sleeve construction which employs a matrix of hot-melt glue dots printed on one surface thereof for the purpose of maintaining a preselected distance between the sleeve and a complimentary beverage cup, around which the sleeve is wrapped. According to such a construction, the glue dots (and not the paperboard sleeve onto which the dots are printed) contact the outer surface of the cup, thereby defining an air gap between the sleeve and the cup such that a user's fingers gripping the sleeve will not be burned by the cup. However, there remains a need to improve upon an overall container construction incorporating such a technique for maintaining an air gap between complimentary walls of a double-wall beverage container.
Single layer paper cup technology does not have the ability to keep beverages or drinks warm, and at the same time protect the hand from becoming uncomfortable from holding a hot liquid or material. Similarly, a simple single layer cup or container construction does not have the ability to insulate a cold beverage or product and protect the exterior of the cold container from moisture condensation that can pool on the bottom of the container and stain furniture or the interior finish of cars and vehicles.
Many past container products have used very expensive solutions, such as an insulated foam laminate or a corrugated paper spacer to create cup sidewall thickness and this attempt to create hand-hold protection, in addition to heat- and cold-retention in the beverage or food product contained therein. All of the built-up laminated approaches to producing a thick-walled insulated cup require very unique and expensive converting equipment to manufacture a blank used to form the cup, plus an additional piece of equipment to wrap the resulting blank into a cup or container. A more simplified and high-speed system is required that could replace the high cost of a specialty blank converting manufacturing system.